It is known that an organic polymer having at least one reactive silicon group in the molecule has an interesting property such that even at room temperature the organic polymer yields a rubber-like cured substance through cross-linking based on the formation of a siloxane bond involving the hydrolysis reaction of the reactive silicon group caused by moisture and the like.
Among these reactive silicon group-containing polymers, polyoxyalkylene polymers and polyisobutylene polymers, which are disclosed in (Patent Document 1), (Patent Document 2), (Patent Document 3), (Patent Document 4), (Patent Document 5), (Patent Document 6), (Patent Document 7), and the like, have already been industrially produced to be widely used in applications to sealants, adhesives, coating materials and the like.
When resins for use in adhesives used as adhesives for interior panels, adhesives for external panels, adhesives for tiling, adhesives for stone tiling, adhesives for finishing walls and adhesives for vehicle panels and the like are poor in recovery property and creep resistance, the adhesive layers are distorted with time due to the weights of the adherends and external stress to displace panels, tiles and stone pieces as the case may be. Additionally, when adhesives for finishing ceilings and adhesives for finishing floors are poor in recovery property and creep resistance, the adhesive layers are distorted with time to form irregularities on the ceiling surfaces and floor surfaces as the case may be. Moreover, adhesives for assembling electric, electronic and precision instruments are poor in recovery property and creep resistance, the adhesive layers are distorted with time to lead to performance degradation of these instruments as the case may be. Accordingly, the compositions to be used in these adhesives are required to be excellent in recovery property and creep resistance.
Sealants are generally used for the purpose of imparting water tightness and air tightness by filling these materials in the joints and gaps between various members. Accordingly, because the property to follow over a long period the portions to which these adhesives are used is extremely important, the physical properties of the cured substances of these adhesives are required to be excellent both in recovery property and in durability. Particularly, excellent recovery property and durability are required for compositions to be used for sealants for working joints in buildings with large joint variation (cap pieces, periphery of window glass, periphery of window frame/window sash, curtain wall, various exterior panels), sealants for direct glazing, sealants for double glazing, sealants for the SSG technique and the like.
The curable compositions containing these reactive silicon group-containing organic polymers are cured by use of silanol condensation catalysts; usually organotin based catalysts having carbon-tin bonds such as dibutyltin bis(acetylacetonate) are widely used. However, in these years, organotin compounds have been pointed out to have toxicity, and additionally, there is a drawback such that the use of organotin catalysts degrades the recovery property and the creep resistance of curable compositions.
On the other hand, as described in (Patent Document 8), (Patent Document 9), (Patent Document 10) and (Patent Document 11), divalent tin carboxylates can also be used as silanol condensation catalysts. The use of these divalent tin carboxylates yields cured substances improved in recovery ratio and creep resistance. The use of divalent tin carboxylates in combination with amine compounds can improve the curability.
However, there has been a problem that the curability of a one-part curable composition prepared by use of a divalent tin catalyst is found to be degraded after storage. (Patent Document 11) discloses a technique which does not cause the curing retardation after storage by virtue of using a non-phthalate based plasticizer even when a divalent tin catalyst is used.
Additionally, (Patent Document 12) describes a technique to decrease the stress while a high recovery ratio is maintained, by adding an acid and an amine compound each in a content larger than the equimolecular amount in relation to a tin-type curing catalyst.    [Patent Document 1] Japanese Patent Laid-Open No. 52-73998    [Patent Document 2] Japanese Patent Laid-Open No. 5-125272    [Patent Document 3] Japanese Patent Laid-Open No. 3-72527    [Patent Document 4] Japanese Patent Laid-Open No. 63-6003    [Patent Document 5] Japanese Patent Laid-Open No. 63-6041    [Patent Document 6] Japanese Patent Laid-Open No. 1-38407    [Patent Document 7] Japanese Patent Laid-Open No. 8-231758    [Patent Document 8] Japanese Patent Laid-Open No. 55-9669    [Patent Document 9] Japanese Patent No. 3062626    [Patent Document 10] Japanese Patent Laid-Open No. 6-322251    [Patent Document 11] Japanese Patent Laid-Open No. 2000-345054    [Patent Document 12] Japanese Patent Laid-Open No. 11-116686